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Subject[PATCH 1/2] perf/x86/utils: fix uninitialized var in get_branch_type()
From
offset is passed as a pointer and on certain call path is not set by the
function. If the caller does not re-initialize offset between calls, value
could be inherited between calls. Prevent this by initializing offset on each
call.
This impacts the code in amd_pmu_lbr_filter() which does
for(i=0; ...) {
ret = get_branch_type_fused(..., &offset);
if (offset)
lbr_entries[i].from += offset;
}

Signed-off-by: Stephane Eranian <eranian@google.com>
---
arch/x86/events/utils.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/events/utils.c b/arch/x86/events/utils.c
index 5f5617afde79..76b1f8bb0fd5 100644
--- a/arch/x86/events/utils.c
+++ b/arch/x86/events/utils.c
@@ -94,6 +94,10 @@ static int get_branch_type(unsigned long from, unsigned long to, int abort,
u8 buf[MAX_INSN_SIZE];
int is64 = 0;

+ /* make sure we initialize offset */
+ if (offset)
+ *offset = 0;
+
to_plm = kernel_ip(to) ? X86_BR_KERNEL : X86_BR_USER;
from_plm = kernel_ip(from) ? X86_BR_KERNEL : X86_BR_USER;

--
2.37.3.998.g577e59143f-goog
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